Animal models have suggested that glutamate neurotoxicity or metabolic impairment may cause neurodegeneration in HD. Remacemide, a drug with glutamate antagonist properties, has been safely tested in HD patients. Co-Enzyme Q10, a metabolic enhancer, has shown preliminary success in reversing metabolic markers of HD. This double-blind, This research study will evaluate the effects of Co-enzyme Q10 and Remacemide on the symptoms of Huntington's Disease (HD). The brain cell death that is the cause of HD is thought to be possibly caused by a) over-activity of the natural brain chemical glutamate, b) a lack of normal cell energy, or c) harmful brain substances called free radicals. Remacemide is an experimental drug that may be useful in treating HD by adjusting the activity of glutamate in the brain. Co-enzyme Q10 (CoQ) is a marketed product that may be useful in HD because it increases cell energy and decreases free radicals. This study will evaluate the potential benefits and safety of remacemide and CoQ, alone or in combination, on the features of HD.